Electric furnace



E. H. HORSTKOTTE.

-ELECWG FURNACE.

UUTLET 'Im/@WHW Edward "Lukotte H. i@ om Patented Sept; 5., 1922.

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Application filed. May 3,

To EZZ 'whom t may concern.'

Be it known that I, EDWARD H. HORST- Kor'rn, a citizen of the United States, resid ing at Schenectady, inthe county of Schenectady, State of New York, have invented certain new and useful improvements in Electric Furnaces, of which the following` is a speciication.

The present invention comprises an electric resistance furnace which is adapted particularlyfor melting materials and treating -molten charges.

It has been suggested heretofore to provide electric furnaces with heaters of the immersion type in which a resistor, such for example, as granular carbon was packed into the space between a tube of carbonaceous material constituting one electrode and a carbon rod constituting the opposite electrode. ln this case the electric current could pass in an irregular manner from an inner core electrode through the resistance mate rial to the outer tube, resulting in a poor distribution of the current and local overheating.

In accordance with my invention, I have provided a furnace containing a resistor contained within a refractory housing-but located out of contact with the housing. Preferably, I employ a resistor consisting of plates, or discs, of suitable resistance material arranged in a stack contained within a housinr of refractory material, but spaced away fiom said housing. -Preferably these plates make a marginal contact only with each other to favor the radiation of the heat from the resistor to the housing,- which preferably is in contact with the charge.

A11-embodiment of my invention is illustrated in vertical longitudinal section in Fig. 1; in Fig. 2 l have illustrated in section two units of one form of resistance heater suitable for use in connection with my invention.

Referring to Fig. l, the furnace illustrated comprises a container consisting of suitable refractory brick 1, Surrounded by a casing,r 2 of sheet metal or the like. The bottom of the furnace chamber 3 contains a block or bed 4 of conducting material, as for examnr plc, carbon or graphite, and in contact there with are resistors 5, 6, connected in Series throuwh the bed 4 to the secondary f a. transibrmer 7. Surrounding the resistors 1920. Serial No. @5,39%

are, refractory housings 8, t), which may connnwnnn n. nons'rnorrn, or sonlnnncranr, New Yoan, assienon 'ro emanan w sist of carbonaceous material, such as graphe ite, silicon carbide, silicon-carbo1i-onygen compounds, alundum or other suitable materials. In the embodiment illustrated in Fig. l the housings 8, 9 consist of conducting material such as graphite, the circuit through the resistors 5, 6, being completed through the bottom of the resistor housings. The resistors 5, 6, consist of a stack of plates, or discs, which are preferably thinnest at the lowermost section where the greatest amount of heat is to be generated. As a. considerable portion of the resistance of a heating unit as here described consists of contact resistance which is not materially changed by temperature variation, a carbonA pile resistor has desirable characteristics as a furnace heater.

As shown in Fig. 2 these plates may' be somewhat dished in shape, the central vvportions 11 being spaced out of contact while the peripheral zone l2 is in contact so as to generate the heat as near the inner wall of the protective housing as possible. Cem trail located holes are provided to facili tate introduction of the plates into the housings 8, 9. The heat generated at the peripheral section is radiated to the housings which in turn are in direct contact with a molten charge l() consisting, for example, of brass or copper. Suitable water cooling collars 13, 1li may be provided adjacent the projecting ends of the electrodes 5, 6.

Various modifications may be made within the spirit of my invention. For example, the resistor ma be modified in various ways, the sleeved resistor may be used in the furnace in various positions and operated with sources of current other than single phase.

When the resistor housing consists of nonconducting material, such, for example, as.`

alundum, a conducting plug can he inserted at the lower end of the housing in order to complete the electrical circuit.

What I claim as new and desire to secure by Letters Patent of the United States, is 1. An electric furnace comprising a container, a resistance heater therein comprising a plurality ,of (lished discs in electrical contact at a peripheral zone but out of contact at a centra lportion and a refractory shield located between said heater and charge in said furnace.

2. An electric furnace comprising a housing, a conductor located at the base of said housing consisting of carbonaceous material, 'a plurality of heaters comprising stacked dif-ses making electrical Contact with each other at an annular peripheral zone and in circuit with said conduct-or, sleeves of re- Atractory material surrounding said disc heat-ers and means; for conducting an elec trical heating current through said resistors in Series, substantially independently of said sleeves.

3. An electric furnace comprising a charge-containing receptacle, a resistance heater, a refractory sleeve for Said heater in Contact with one end of said heater but spaced away from said heater intermediate the terminals thereof, and means for conveyingr a heating current to :sairl heater independently of said sleeve.

4. An electric Jfurnace comprising a Substantially closed container, a'conductor con sisting of earbonaceous material located at the base of said container, a plurality of graphite tubes each having a closed and making electrical Contact with said cominctor, a stack of graphite discs in said tubes but out ot electrical contact with the Sides of said tubes7 electrodes of carbonaceous Inaterial making Contact with saitl stacks of discs and a source of heating current connectetl to said electrodes.

In witness hereof` l have hereunto set my hand this lst day of May, 1920.

EDlVARD H. HORSTKOTTE. 

